KR20210075502A - Method for recovering valuable metals from cathodic active material of used lithium battery - Google Patents

Abstract

The present invention relates to a method for recovering valuable metals from a positive electrode active material of a wasted lithium battery, which includes: heat-treating a positive electrode material of a wasted lithium ion battery; adding the positive electrode material of the heat-treated wasted lithium ion battery to an aqueous solution containing a calcium compound to obtain a leachate containing lithium; separating the leachate into solid-liquid; concentrating the solid-liquid separated leachate to obtain lithium hydroxide; washing the lithium hydroxide with water; and dissolving the lithium hydroxide after washing with water and re-concentrating the lithium hydroxide. According to the present invention, a high concentration of lithium can be recovered from the lithium positive electrode material of a wasted lithium ion battery, and thus, the lithium recovery rate and economic efficiency can be improved. In addition, it is possible to recover valuable metals, such as nickel, cobalt, and manganese other than lithium in a solid form. Further, it is possible to recover valuable metals, such as nickel, cobalt, and manganese other than lithium in a solid form.

Description

Method for recovering valuable metals from cathode materials of spent lithium ion batteries {METHOD FOR RECOVERING VALUABLE METALS FROM CATHODIC ACTIVE MATERIAL OF USED LITHIUM BATTERY}

The present invention relates to a method for recovering valuable metals from a cathode material of a spent lithium ion battery.

Lithium ion batteries are used as power sources for small portable equipment because of their high energy density and light weight, and the use of lithium ion batteries is rapidly increasing in recent years. In particular, in recent years, it has been widely used as a power source for not only small home appliances and mobile products, but also hybrid electric vehicles (HEV/EV).

Such a lithium ion battery is composed of a positive electrode, a negative electrode, an electrolyte and a separator, and specifically, a plastic casing and a positive electrode, a negative electrode, a separator, an electrolyte, and a nickel-coated steel case contained in several cell units. (Ni-coated steel casing).

On the other hand, the positive electrode of a lithium ion battery consists of an active cathode material, a conductive agent, a binder, and a current collector, and as a positive electrode material, it has excellent reversibility, low self-discharge rate, high capacity, and high energy density. , lithium cobalt oxide (LiCoO ₂ ), which is easy to synthesize, is widely used.

In addition, in recent years, in order to reduce the amount of expensive cobalt (Co) used, a ternary lithium composite metal oxide such as Li(NiCoMn)Ox containing Ni and Mn is also used as a cathode material. However, since all of the above cathode materials contain a large amount of valuable metals such as lithium, nickel, cobalt, and manganese in at least 5% by weight or more, it is difficult to recover expensive valuable metals from the cathode material (positive electrode material scrap) of the spent lithium ion battery. Attention is drawn to how to

The cathode material scrap is roughly divided into the so-called process scrap generated during the manufacturing process of the cathode material or lithium ion battery, and the so-called waste scrap obtained through various separation or selection processes from the spent lithium ion battery after use. The former process scrap contains almost no impurities such as carbon, but the latter waste scrap contains impurities such as carbon because the materials constituting the lithium ion battery such as anode material cannot be completely removed due to the nature of the separation or selection process. has been

In this regard, Patent Document 1 provides a method of recovering lithium by reducing cathode material scrap with hydrogen or carbon. In the case of reduction with hydrogen, lithium becomes lithium hydroxide (LiOH) and the concentration of lithium in the solution recovered through washing with water increases, because the solubility of LiOH in water is as high as 30-50 g/L based on lithium. However, in the case of reduction to carbon, since lithium becomes lithium carbonate (Li ₂ CO ₃ ) in the reduction process, the lithium concentration in the solution recovered through washing with water is low. This is because _{the solubility of Li 2} CO ₃ in water is as low as 1-3 g/L based on lithium.

As described above, in order to recover lithium from a solution having a low lithium concentration, it has to go through an evaporation and concentration process. As the lithium concentration is low, the amount of water to be evaporated relatively increases, and thus energy cost increases.

As described above, so-called waste scrap contains carbon, whereby lithium is converted into _{Li 2} CO _{3 in the reduction process.} Therefore, according to the method disclosed in Patent Document 1, there is a problem in that economic efficiency is lowered because a solution having too low lithium concentration has to be obtained.

Republic of Korea Patent Registration No. 10-1497041

An object of the present invention is to propose a method for recovering lithium in the form of a high-concentration solution regardless of the type of secondary battery cathode material scrap. In addition, a method for removing impurities contained in the recovered lithium solution and a method for recovering other valuable metals such as nickel, cobalt, and manganese are also presented.

According to one aspect of the present invention, the method comprising: heat-treating a cathode material of a waste lithium ion battery; adding a cathode material of the heat-treated waste lithium ion battery to an aqueous solution containing a calcium compound to obtain a leachate containing lithium; separating the leachate into solid-liquid; concentrating the solid-liquid separated leachate to obtain lithium hydroxide; washing the lithium hydroxide with water; And there is provided a method for recovering valuable metals from a cathode material of a waste lithium ion battery comprising the step of dissolving the lithium hydroxide after washing with water and then re-concentrating.

In the step of heat-treating the cathode material of the waste lithium ion battery, a carbon-containing compound may be added.

The carbon-containing compound may be at least one selected from graphite, bituminous coal, and anthracite coal.

The input amount of the carbon-containing compound may be 1.5 to 5 times the weight of lithium contained in the cathode material of the spent lithium ion battery.

The heat treatment may be performed in a reducing atmosphere in a temperature range of 450 to 1000 °C.

The heat treatment may be performed by introducing at least one reducing gas selected from nitrogen and argon.

The concentration of the calcium compound in the aqueous solution containing the calcium compound may be 50 g / L to 100 g / L.

The temperature of the aqueous solution containing the calcium compound may be 50 to 99 ℃.

The calcium compound may be at least one selected from calcium hydroxide, calcium oxide, slaked lime, and quicklime.

The concentration may be concentrated by evaporation at a temperature of 50 °C to 100 °C.

The re-concentration may be concentrated by evaporation at a temperature of 50 °C to 100 °C.

The method may include acid leaching or solvent extraction of the residue obtained after the solid-liquid separation to obtain at least one selected from nickel, cobalt, manganese and aluminum.

According to the present invention, it is possible to recover a high concentration of lithium from the cathode material of a waste lithium ion battery, and thus, it is possible to improve the lithium recovery rate and economic efficiency. In addition, it is possible to recover valuable metals other than lithium, such as nickel, cobalt, and manganese in a solid form.

Hereinafter, preferred embodiments of the present invention will be described with reference to various examples. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a method for recovering valuable metals from a cathode material of a spent lithium ion battery.

According to one aspect of the present invention, the method comprising: heat-treating a cathode material of a waste lithium ion battery; adding a cathode material of the heat-treated waste lithium ion battery to an aqueous solution containing a calcium compound to obtain a leachate containing lithium; separating the leachate into solid-liquid; concentrating the solid-liquid separated leachate to obtain lithium hydroxide; washing the lithium hydroxide with water; And there is provided a method for recovering valuable metals from a cathode material of a waste lithium ion battery comprising the step of dissolving the lithium hydroxide after washing with water and then re-concentrating.

In the present invention, the cathode material of the waste lithium ion battery includes both the cathode material or process scrap generated during the manufacturing process of the lithium ion battery and the waste scrap obtained through various separation or selection processes from the waste lithium ion battery after use. The cathode material of the waste lithium ion battery is not particularly limited, lithium nickel cobalt aluminum oxide (LiNiCoAlO ₂ , NCA), lithium nickel cobalt manganese oxide (LiNiCoMnO ₂ , NCM), lithium iron _{phosphate oxide (LiFePO 4} , LFP), lithium manganese iron phosphate (LiMnFePO _4, LMFP), lithium manganese oxide (LiMn ₂ O _4, LMO), and lithium nickel-manganese spinel _{(LiNi 0. 5 Mn 1.} 5 O 4, LNMO), lithium cobalt oxide (LiCoO _2, LCO) It may include one or more selected from among. Accordingly, the cathode material of the waste lithium ion battery may include at least one valuable metal selected from the group consisting of nickel, cobalt, manganese and lithium.

The heat treatment is preferably carried out in a reducing atmosphere having a low oxygen concentration. When the cathode material of a waste lithium ion battery is directly heated, the oxygen concentration can be controlled low through incomplete combustion, and when the cathode material of a waste lithium ion battery is indirectly heated, one or more reducing properties selected from nitrogen and argon in the heat treatment device It is preferable to introduce a gas to create a reducing atmosphere. The heat treatment may be performed using a rotary kiln in consideration of reactivity and productivity, but the present invention is not limited to using a rotary kiln, and any device capable of high temperature heat treatment may be used.

On the other hand, the heat treatment is preferably performed in a temperature range of 450 to 1000 ℃. If it is less than 450 ℃, the reduction reaction rate is too slow to ensure productivity, whereas, if it exceeds 1000 ℃, sintering or melting may occur, which may cause a problem that is difficult to apply industrially.

On the other hand, if necessary, in the step of heat-treating the cathode material of the waste lithium ion battery, a carbon-containing compound may be added and heat treatment may be performed. More specifically, the cathode material of a waste lithium ion battery containing a carbon component sufficiently, for example, 25% by weight or more, is subjected to heat treatment as it is, and contains no or insufficient carbon component, for example, less than 25% by weight. It is preferable to convert the _{lithium component into the form of lithium carbonate (Li2CO 3} ) by adding a carbon-containing compound to the cathode material of the spent lithium ion battery and performing heat treatment.

The carbon-containing compound is not particularly limited, and may be, for example, at least one selected from graphite, bituminous coal, and anthracite coal.

The carbon-containing compound is preferably added in an amount of 1.5 to 5 times the weight of lithium contained in the cathode material of the spent lithium ion battery. When the amount is less than 1.5 times, the reduction is insufficient and the conversion reaction to lithium carbonate is also insufficient. Accordingly, there is a problem in that the recovery rate of lithium in the subsequent lithium recovery process is lowered, and when it is more than 5 times, the cost not only increases It becomes a factor of increasing waste in the post-process.

Next, the cathode material of the heat-treated waste lithium ion battery is put into an aqueous solution containing a calcium compound to obtain a leachate containing lithium. Nickel, cobalt, manganese, etc. contained in the positive electrode material of the heat-treated waste lithium ion battery is reduced to cause dissociation with lithium, and lithium is present in the form of lithium carbonate by the carbon component. In order to leach lithium from the cathode material of the heat-treated waste lithium ion battery, it is added to water and reacted with a calcium compound to convert lithium carbonate into lithium hydroxide (LiOH), thereby obtaining a leachate having a high lithium concentration. More specifically, since the solubility of lithium carbonate in water is as low as 1 to 3 g/L based on lithium, while lithium hydroxide is as high as 30 to 50 g/L, it is possible to increase the lithium concentration in the solution through reaction with a calcium compound. it is preferable

The calcium compound is not particularly limited, but may be, for example, at least one selected from calcium hydroxide, calcium oxide, slaked lime and quicklime. When the calcium compound is calcium hydroxide, the reaction formula of lithium carbonate and calcium hydroxide in the cathode material of the spent lithium ion battery is as follows.

[Formula 1]

Li ₂ CO ₃ + Ca(OH) ₂ → 2LiOH + CaCO ₃

The concentration of the calcium compound in the aqueous solution containing the calcium compound is preferably 50g/L to 100g/L. If it is less than 50 g/L, the reaction may occur insufficiently, and if it exceeds 100 g/L g/L, not only cost increases, but also becomes a factor of increasing waste in the post-process.

The temperature of the aqueous solution containing the calcium compound is preferably 50 ℃ or more and less than 100 ℃. When the temperature is less than 50°C, the reaction rate is too slow, and when it exceeds 99°C and becomes 100°C, an additional energy consumption problem may occur due to boiling of water.

After obtaining the lithium-containing leachate, a solid-liquid separation step may be performed to separate the residue and the leachate. Here, metal elements such as nickel, cobalt, manganese, and aluminum are separated into cake residues, and lithium is separated in a dissolved state in the leachate. Thereafter, the residue is separated and recovered as elements such as nickel, cobalt, manganese, and aluminum through sulfuric acid leaching or solvent extraction process, which is used as a raw material to be synthesized as a precursor of a secondary battery cathode material and recycled can do. Meanwhile, solid-liquid separation may be performed using a conventional solid-liquid separation equipment such as a filter press.

The solid-liquid separated leachate is concentrated to obtain solid lithium hydroxide. The concentration is preferably concentrated by evaporation at a temperature of 50 °C to 100 °C. When the temperature is 50° C. or less, the concentration rate is too slow, and when it reaches 100° C., the temperature of the water does not rise any more, so a temperature of 100° C. or less is preferable.

Even after the solid-liquid separation process, the leachate contains impurities. Therefore, in order to manufacture high-purity lithium hydroxide that can be used as a cathode material for a secondary battery, it is preferable to wash the obtained solid lithium hydroxide with water to remove impurities. The water washing may be performed using distilled water or deionized water.

As described above, by re-dissolving solid lithium hydroxide from which impurities have been removed in water and re-concentrating it, high-purity lithium hydroxide can be obtained. The re-concentration is preferably concentrated by evaporation at a temperature of 50 °C to 100 °C. When the temperature is 50° C. or less, the concentration rate is too slow, and when it reaches 100° C., the temperature of the water does not rise any more, so a temperature of 100° C. or less is preferable.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Example

A cathode material of a waste lithium ion battery having the components and contents of Table 1 below was heat-treated in a nitrogen atmosphere and 600° C. for 1 hour. Since the cathode material contained 29 wt% of carbon, it was not necessary to add an additional carbon-containing compound. After the heat-treated cathode material of the waste lithium ion battery was reacted with water containing 70 g/L of calcium hydroxide at 90° C. for 1 hour, solid-liquid separation was performed.

The leachate from which the residue was separated through solid-liquid separation was concentrated at 80° C. for 2 hours to obtain solid lithium hydroxide. The solid lithium hydroxide was washed with distilled water and then dissolved again in water, and the composition of the solution is shown in Table 2.

ingredient Li Ni Co Mn C content (wt%) 3.3 14.4 5.4 7.5 29

ingredient Li Ni Co Mn Content (g/L) 12.3 <0.01 <0.01 <0.01

Referring to Table 2, it can be seen that the lithium concentration in the solution is very high as 12.3 g/L, which means that lithium carbonate in the cathode material of the heat-treated waste lithium ion battery is converted to lithium hydroxide, and impurities are removed through washing with water. It can be considered as a result. Trace elements other than lithium remain almost entirely in solid form, and nickel, cobalt, and manganese can be recovered by leaching, refining, and solvent extraction therefrom. It was confirmed that a solution having a high lithium concentration can be obtained by using the series of methods shown above, and nickel, cobalt, and manganese can be recovered in solid form.

comparative example

The cathode material of the waste lithium ion battery having the components and contents of Table 1 was heat-treated in a nitrogen atmosphere and 600° C. for 1 hour. After the cathode material of the heat-treated waste lithium ion battery was put into water and leached, solid-liquid separation was performed, and the components and composition of the leaching solution are shown in Table 3 below.

ingredient Li Ni Co Mn Content (g/L) 2.8 <0.01 <0.01 <0.01

Referring to Table 3, it can be seen that the lithium concentration in the leachate was 2.8 g/L, which was significantly lower than that of the Example. This can be judged as a result of the fact that lithium in the cathode material of the heat-treated waste lithium ion battery is present in the form of lithium carbonate, and purification by concentration, washing and re-concentration is not performed.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.

Claims (12)

heat-treating the cathode material of the spent lithium-ion battery;
adding a cathode material of the heat-treated waste lithium ion battery to an aqueous solution containing a calcium compound to obtain a leachate containing lithium;
separating the leachate into solid-liquid;
concentrating the solid-liquid separated leachate to obtain lithium hydroxide;
washing the lithium hydroxide with water; and
A method for recovering valuable metals from a cathode material of a waste lithium ion battery comprising the step of dissolving the washed lithium hydroxide in water and then re-concentrating.
According to claim 1,
In the step of heat-treating the cathode material of the waste lithium ion battery, a method for recovering valuable metals from the cathode material of a waste lithium ion battery, characterized in that by adding a carbon-containing compound.
3. The method of claim 2,
The carbon-containing compound is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that at least one selected from graphite, bituminous coal and anthracite.
3. The method of claim 2,
The method for recovering valuable metals from the cathode material of a waste lithium ion battery, characterized in that the input amount of the carbon-containing compound is 1.5 to 5 times the weight of lithium contained in the cathode material of the waste lithium ion battery.
According to claim 1,
The heat treatment is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that it is performed in a temperature range of 450 to 1000 °C in a reducing atmosphere.
6. The method of claim 5
The heat treatment is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that it is performed by introducing at least one reducing gas selected from nitrogen and argon.
According to claim 1,
The method for recovering valuable metals from the cathode material of a waste lithium ion battery, characterized in that the concentration of the calcium compound in the aqueous solution containing the calcium compound is 50g/L to 100g/L.
According to claim 1,
The method for recovering valuable metals from the cathode material of a waste lithium ion battery, characterized in that the temperature of the aqueous solution containing the calcium compound is 50 to 99 ℃.
According to claim 1,
The calcium compound is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that at least one selected from calcium hydroxide, calcium oxide, slaked lime and quicklime.
According to claim 1,
The concentration is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that the concentration is concentrated by evaporation at a temperature of 50°C to 100°C.
According to claim 1,
The re-concentration is a method for recovering valuable metals from a cathode material of a waste lithium ion battery, characterized in that evaporation and concentration at a temperature of 50°C to 100°C.
According to claim 1,
A method for recovering valuable metals from a cathode material of a waste lithium ion battery, comprising the step of obtaining at least one selected from nickel, cobalt, manganese and aluminum by acid leaching or solvent extraction of the residue obtained after the solid-liquid separation.